An artificial reality system, such as a head-mounted display (HMD) or heads-up display (HUD) system, generally includes a display configured to present artificial images that depict objects in a virtual environment. The display may display virtual objects or combine real objects with virtual objects, as in virtual reality (VR), augmented reality (AR), or mixed reality (MR) applications. For example, in an AR system, a user may view both displayed images of virtual objects (e.g., computer-generated images (CGIs)) and the surrounding environment by, for example, seeing through transparent display glasses or lenses (often referred to as optical see-through) or viewing displayed images of the surrounding environment captured by a camera (often referred to as video see-through).
The user experience of using an artificial reality system may depend on several optical characteristics of the artificial reality system, such as the field of view (FOV), image quality (e.g., resolution), size of the eye box (to accommodate for eye and head movement), brightness of the displayed image, and the like. In general, the FOV and the eye box should be as large as possible, the resolution (e.g., the total number of pixels or angular resolution) should be as high as possible, and the brightness of the displayed image should be high enough (especially for optical see-through AR systems). For example, the eye box should allow for pupil movement caused by environmental use of the system (e.g., rotation of the eye and shift of the AR system), and allow for comfortable viewing of a large FOV with a desirable resolution. HMDs that provide only a small eye box may substantially impair the user experience, because the CGI images can be impaired, or even disappear from the user's vision, with a slight bump of the HMD or eye motions. However, increasing the eye box of the system may lead to a larger, heavier, more expensive, and less energy-effective system.